How to create CSV with values before executing a Scenario

Hi,
I have the following use-case - I need to test an HTTP API, with dynamic values, that are retrieved from an external datastore (not SQL). Ideally I would like these values to be fetched from the datastore in a batch operation before the scenario executes, and all VU's use these retrieved values. Is there a way to achieve this? i.e., an option to execute custom code and populate a list / csv variable, before all scenario / userpath executes. I only see an option to execute custom code in the user path, per virtual user, which is not ideal in my use-case. Please advise. thanks!